Generally, a clamshell device comprises two assemblies hinged with each other, wherein one assembly is often known as cover module, and the other assembly is often known as base module. In prior art clamshell devices, the cover module may not be very steadily held at the open angle when the cover module is at an open angle with respect to the base module. For example, a common clamshell device may be a clamshell notebook computer, and where the cover module is at an open angle, if its cover module (i.e., LCD module) is slightly touched or contacted by a finger, substantial wobble may occur to the cover module. However, such wobble is generally undesired.